interface SemaphoreLib {
	int newInstance()
	void wait(int hnd)
	void signal(int hnd)
	void destroy(int hnd)
	}

component provides Semaphore(Destructor) requires native SemaphoreLib lib {
	int hnd
	/* {"@description" : "Instantiate a new semaphore object, initialised with a count of zero." } */
	Semaphore:Semaphore()
		{
		hnd = lib.newInstance()
		if (hnd == 0) throw new Exception("failed to initialise semaphore")
		}
	
	/* {"@description" : "Decrement the semaphore's value, or if zero wait until a thread calls signal()." } */
	void Semaphore:wait()
		{
		lib.wait(hnd)
		}

	/* {"@description" : "Iincrement semaphore's value, unblocking a wait() if the semaphore was previously zero." } */
	void Semaphore:signal()
		{
		lib.signal(hnd)
		}
	
	void Destructor:destroy()
		{
		lib.destroy(hnd)
		}
	
	}